| 摘要 |
PURPOSE:To prevent radio interference by providing a radio interference discriminating section detecting an amplitude modulation component of a received return signal to discriminate the presence of radio interference. CONSTITUTION:The bidirectional communication system is constituted by brand- connecting one signal cable with many terminal devices transmitting a transmission signal whose carrier wave is FSK-modulated by a data signal including an address data, and a central controller provided with a converter section transmitting a return signal converting the carrier frequecy of the transmission signal from each terminal device. In a data receiving section of each terminal device, the data of return signal is fetched when the return signal including the address data coincident with the own address is received. The radio interference discriminating section 27 discriminates the presence of radio interference by detecting the amplitude modulation component of the received return signal, and outputs a radio interference detecting signal VM to an information output circuit 10 to stop the transmission of data. |
